A variety of air admittance valves have been made over the years for allowing air to enter a piping system or an enclosed environment under a negative or vacuum pressure, which is created when water is flowing down the drain for instance thus to preventing siphoning of traps or when a sump pump keeps pumping water and air out of an enclosed sump pit. Attaching an air admittance valve allows ambient air to enter the enclosed environment to eliminate negative pressure or vacuum in the enclosed system. Many of these products are specifically or only designed for systems such as piping systems and sewer systems where a local vent or air intake is not possible or due to the difficulty of running pipes through an already built home. Typically, these air admittance valves only provide specific operating conditions such as the vacuum pressure in the amount of air required. The air admittance valves available in the market today do not provide for an instantaneous and higher volume of air demand. And this causes a problem when existing air admittance components are installed on systems requiring the higher air flow demand. This problem causes strain on the air admittance component and cause it to fail prematurely in addition it causes it to operate against its own design because it was designed to work on a natural gravity air flow vacuum or negative pressure constraint. Also it is a problem that the air admittance valves not working at all or failing immediately when a high air flow demand is required. Furthermore, another problem is that air admittance components available do not filter the air and therefore can allow for corrosive environment to enter the system and damaging the Air admittance components.
There is also an undesired negative situation that the piping system will generate a negative pressure in the piping system when the flow is drained from the piping system. When negative pressure occurs, the water seals in the U-band or trap will be syphoned out and losses the function to prevent sewer gas to enter the house. Therefore, various air admittance valves have designed to allow air enter a piping system to prevent the negative pressure environment. However, regular air admittance valve is also easy to fail.
For these reasons are users are disappointed when there is no product available on the market that they can use for a higher volume demand in a negative pressure scenario such as an enclosed pit with a pump requiring air to enter the system at the same rate of which it is pumping the water out. For instance, a pump that can pump 20 gallons per minute and would require a large demand of air flow to enter the system so that a vacuum does not occur putting stress on the pump and causing the water discharge to not operate and discharge the water properly. In the case of a sump pump, the pump becomes air locked and runs continuous which causes the pump to overheat, burnout and/or fail causing the area to flood and cause water damage to the building.
In many cases it is also required that after air enters the system that there is a proper seal in place to provide a radon gas, water and airtight seal after the air has been allowed to enter the system and when the pump disengages. It is also required that if failure is to occur on such an air admittance component that it must fail in a closed/sealed position providing continued protection so that no air, water or radon gas can escape into the air within the building or within a certain high of the structures roof line on the exterior.
Although some check valves have the design of a ball inside the valve to stop or open the flow to pass through the valve. However, those ball valve tends to have accumulated scum or fouls on the ball that cause the ball not able to seal the flow properly.
Another issue currently in the market is that the detection of the leakage of the valve is not easy. Since the valve has one end connected to the ambient air and one end to the plumbing system or the enclosed environment, the pressure status detected is either the ambient environment's pressure or the plumbing system's pressure. Those two pressure cannot be used to detect whether the valve is leaked or not. Often the valve is worn out and the valve seat cannot seal the foul air very well. The leakage might be subtle. Therefore, it is hard to detect from the ambient air pressure or the pressure in the plumbing system, which varied in accordance to the flow movement in the plumbing system.
Another problem pertaining to thermal expansion of gasses and the relationship between temperature, volume, and pressure. The following example may illustrate this issue. The air outside and the air inside the building are a constant. So if, the air outside pressure is 1 atm (Atmospheric pressure) at 100° F., then the air inside pressure is 0.946 atm at 70° F. Therefore, the pressure differential is −0.054 atm at a the 30° F. temperature differential. Since the sealing member for ambient zone opening pressure is 0.001 atm the valve would leak foul gas into the ambient pressure zone with only −1° F. of temperature change from outside to inside.
Another issue also crucial to the current air admittance valve in the market is that there is no double assurance in single valve to ensure that failure of the valve can be made up by other mechanism. Often, the current practice is to install two check valves inline, which is problematic that this practice causes too much connecting spaces and extra works, and the losses of energy due to the energy losses in multiple connection entrances. Therefore, there is a long-felt need to resolve aforementioned issues.